| 摘要 |
PURPOSE:To minimize the material loss in manufacturing a special oil well pipe by executing the necessary final heat treatment on the blank pipe manufactured by deciding the manufacturing target values of the outer diameter and thickness at the same or about the same value as the nominal value of the specifications and by executing a swaging by an integral type cylindrical die on both the pipe end parts thereof. CONSTITUTION:A blank pipe 6 is manufactured by an ordinary method in the dimension at the same or about the same aiming value with the specification nominal value stipulated for in API standard on the oil well pipe to be manufactured. The swaging accompanying no thickness increase unnecessarily by an integral type cylindrical die 1 or 1' is executed on the pipe end part after performing the necessary final heat treatment for this blank pipe 6. The pipe end part becomes in the shape running along the inner part of the cylindrical die 1 by inserting the cylindrical die 1 into the pipe end part of the blank pipe 6, since the inlet side of the cylindrical die 1 for forming a male thread becomes smaller than the larger diameter part 7 than the outer bore of the pipe main body part, the inner part thereof a taper part 8 and diameter inner part thereof than the outer diameter of the pipe main body part A. taper thread cutting is thereafter executed on the pipe end part after performing a stress removing annealing.
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